For All This Time, Protons Have Been Hiding Secret Mass

Usually, when we talk about mass, we’re talking about how much stuff is in an object. Everything from your body to a black hole is made up of matter, and adding all that matter together gives you the mass of an object.
But, just like everything else, mass can get a little screwy in the quantum world. Physicists have been puzzling over why protons are more massive than the matter that makes them up for a long time, and recently, they seem to have figured it out.
For All This Time, Protons Have Been Hiding Secret Mass. We Just Found It.